package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author amanda
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    // 静态代码块，加载Lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("Seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    // 线程池
    private static final ExecutorService SECKILL_ORDEREXECUTOR = Executors.newSingleThreadExecutor();
    // 使用spring注解，即当前对象初始化完毕之后，执行init方法
    @PostConstruct
    private void init() {
        SECKILL_ORDEREXECUTOR.submit(new VoucherOrderHandler());
    }
    // 业务方法，执行处理订单
    private class VoucherOrderHandler implements Runnable {
        String queueName = "stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    // 1. 获取消息队列中的订单信息 xreadgroup group g1 count 1 block 2000 STREAM stream.orders >
                    List<MapRecord<String,Object,Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1","c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2. 判断消息获取是成功
                    if (list == null || list.isEmpty()) {
                        // 2.1 如果获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 3. 解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(),true);
                    // 4.如果获取成功，执行下单业务
                    handleVoucherOrder(voucherOrder);
                    // 5.ACK确认消息 sack stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常！");
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 count 1 streams stream.order 0
                    List<MapRecord<String,Object,Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1","c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    if (list == null || list.isEmpty()) {
                        // 2.获取失败，说明pending-list没有异常信息，结束循环
                        break;
                    }
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(),true);
                    handleVoucherOrder(voucherOrder);
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    log.error("处理pending-list异常！",e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException interruptedException) {
                        interruptedException.printStackTrace();
                    }
                }
            }
        }
    }
    /*
    // 阻塞队列
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private class VoucherOrderHandler implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    // 1. 获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 2. 创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常！");
                }
            }
        }
    }*/

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        // 获取用户id
        Long userId = voucherOrder.getUserId();
        // 创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 获取锁
        boolean isLock = lock.tryLock();
        // 判断是否获取锁成功
        if (!isLock) {
            // 失败
            log.error("不允许重复下单！");
            return;
        }
        try {
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            lock.unlock();
        }
    }
    // 代理对象
    private IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        Long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),userId.toString(),String.valueOf(orderId)
        );
        // 2.判断结果是否为0
        int r = result.intValue();
        if (r != 0 ) {
            // 2.1 不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足!" : "该代金券您已经购买过!");
        }
        // 3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 3.返回订单id
        return Result.ok(orderId);
    }

    /**
     * 使用JVM的阻塞队列
     * @param voucherOrder
     */
    /*@Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),userId.toString()
        );
        // 2.判断结果是否为0
        int r = result.intValue();
        if (r != 0 ) {
            // 2.1 不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足!" : "该代金券您已经购买过!");
        }
        // 2.2 若为0，有购买资格，把下单的信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3 订单id
        Long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4 用户id
        voucherOrder.setUserId(userId);
        // 2.5 代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6 放入阻塞队列
        orderTasks.add(voucherOrder);
        // 3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 3.返回订单id
        return Result.ok(orderId);
    }*/
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 一人一单
        Long userId = voucherOrder.getUserId();
        int count = query().eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId()).count();
        if (count > 0) {
            log.error("该代金券您已经购买过！");
            return;
        }
        // 扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
        if (!success) {
            log.error("库存不足！");
            return;
        }
        // 获取订单
        save(voucherOrder);
    }
    //@Override
    //public Result seckillVoucher(Long voucherId) {
        /*// 查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀还未开始！");
        }
        // 判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束！");
        }
        // 判断库存是否充足
        if (voucher.getStock() < 1) {
            return Result.fail("库存不足！");
        }*/
        /**
         * 悲观锁
         * 这里先添加锁，为了先让spring管理的事务先提交，再释放锁(线程的并发安全)
         * 获取代理对象，当前this对象并没有事务管理的功能
         */
        /*synchronized (UserHolder.getUser().getId().toString().intern()) {
            // 获取代理对象
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        }*/

        /**
         * 基于redis的分布式锁
         * @param voucherOrder*/

        /*Long userId = UserHolder.getUser().getId();
        // 创建锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        // 获取锁，指定锁的名称
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 尝试获取锁，参数分别是获取锁的最大等待时间、锁自动释放时间、时间单位（此处无参表示失败不等待）
        boolean isLock = lock.tryLock();
        // 判断是否获取锁成功
        if (!isLock) {
            // 失败
            return Result.fail("不允许重复下单！");
        }
        try {
            // 获取代理对象
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            lock.unlock();
        }*/
    //}
}
